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GARY N. CALKINS 



The daughter nuclei next divide to form four nuclei, and these 

 in turn form eight, four of which belong to the anterior half, 

 four to the posterior. The lines of densely staining chromatin 

 granules are retained throughout all of these division stages, a 

 characteristic dmiib-bell nucleus being formed at each stage 

 (figs. 15 to 18). During the division from four into eight the 

 cell constriction deepens in the division zone, and the cell divides, 

 the two daughter cells having four nuclei each (figs. 18 and 19). 



Figs. 10, 11 and 12 In figure 10 the nuclei are fully prepared for division; 

 figures 11 and 12 show elongation of the macronucleus and increase of micronuclei 

 to four and six, one degenerating micronucleus in figure 12. X 800. 



The four nuclei finally divide once again, after division of the 

 cell and after separation, and the eight nuclei, characteristic of 

 the normal vegetative phase, are formed (figs. 20 and 21). At 

 each nuclear division the connecting strands are severed so that 

 the daughter nuclei are not connected by any linin or chromatin 

 material. 



The formation and significance of the nuclear cleft after divi- 

 sion is a complicated problem in itself which will be discussed in 



